The present invention relates to an antenna assembly suitable for wireless transmission and receipt of analog and/or digital data, and more particularly to an antenna assembly for use with diverse wireless communication devices.
There are a variety of antennas which are currently used in wireless communication devices. One type of antenna is an external half wave single or multi-band dipole. This antenna typically extends or is extensible from the body of a wireless communication device in a linear fashion during normal operation. Because of the physical configuration of this type of antenna, it is relatively insensitive to directional signal optimization. In other words, it is able to operate in a variety of positions without substantial signal degradation and is considered omni-directional. There is essentially no front-to-back ratio (with respect to a wireless communication device) and little or no Specific Absorption Rate (SAR) reduction with this type of antenna. A typical specific absorption rate for such antennas is 2.7 mw/g at a 0.5 watt transmission power level. With multi-band versions of this type of antenna, where resonances are achieved through the use of inductor-capacitor (LC) traps, gains of +2 dBi are common.
While this type of antenna is acceptable in some wireless communication devices, it has drawbacks. One significant drawback is that the antenna is external to the body of the communication device. This places the antenna in an exposed position where it may be accidentally or deliberately damaged.
A related antenna is an external quarter wave single or multi-band asymmetric wire dipole. This antenna operates much like the aforementioned antenna, but requires an additional quarter wave conductor to produce additional resonances and has drawbacks similar to the aforementioned half wave single or multi-band dipole antenna.
Another type of antenna is the internal single or multi band asymmetric dipole. This type of antenna usually features quarter wave resonant conductor traces, which may be located on a planar printed circuit board within the body of a wireless communication device. Such antennas typically operate over one or more frequency ranges with gains of +1-2 dBi. They also have a slight front-to-back ratio. This antenna may include one or more feed points for multiple band operation, and may require a second conductor for additional band resonance.
Yet another antenna is an internal or single multi-band Planar Inverted xe2x80x9cFxe2x80x9d Antenna (PIFA). This type of antenna features a single or multiple resonant planar conductor that operates over a second conductor or ground plane. With this type of antenna, gains of +1.5 dBi are typical. Front-to-back ratios and SAR values are a function of frequency.
Thus, there exists a need for an antenna assembly which is compact, lightweight and which may be incorporated into a variety of wireless communication devices.
There also exists a need in the art for new varieties of such antenna assemblies that receive and transmit data over two or more distinct frequency bands.
There also exists a need in the art for new varieties of such antenna assemblies that conform to the available interior spacing within a wireless communication device.
A further need exists in the art to maximize use of all available interior volume of a wireless communication device for circuitry used to transmit and receive data and the present invention addresses this need by providing, in one embodiment, additional interior volume for such circuitry to be mounted between operative components of the resonator element and the ground plane of antenna assemblies fabricated according to the present invention.
The present invention as set forth in this disclosure teaches, enables, discloses, illustrates and claims herein a new, useful and non-obvious compact, resonant, slot wedge antenna for wireless communication devices (WCD). The antenna assembly according to the present invention preferably includes the following properties, features and characteristics:
Compact size suitable to integration within a WCD, including without limitation, a telephone device, a personal digital assistant (PDA), and a laptop computer as well as other diverse wireless devices which transmit and receive data via an antenna assembly;
Minimized operational interference by placement of the antenna in a preferred location disposed in an upper portion of the WCD;
Suitable for mounting entirely within the housing of a compact WCD;
Suitable for mounted directly to a related printed wiring board disposed within the interior space of a WCD using known surface mounting techniques;
Robust physical package, or assembly envelop, characterized by having rigidly fixed components and eliminating external appendages of a WCD; and,
Enhanced performance at U.S. cellular frequency range of 824 to 894 MHz as depicted in the appended drawings and with reference to the detailed description of the preferred embodiment of the present invention.
A significant feature of the present invention relates to the sizing of the slot portion of the resonator element. This slot is much smaller than the wavelength of incident radiation, which is a major advantage over previous, prior art slot antenna designs. In a most preferred embodiment, the resonator element from which the slot is cut out or otherwise removed or formed during fabrication of the resonator element is preferably less than one-eighth (xe2x85x9) of the operational wavelength of the 824 to 894 MHz frequency band for which the resonator element is preferably tuned. In order to tune the resonator element (or entire antenna assembly) to a different frequency band of operation, the dimensions for the operative features of the resonator element must be adjusted proportionally.
A resonator element for use in conjunction with a ground plane of a wireless communication device according to the present invention includes first and second conductive portions which are operatively connected to each other by an electrically conducting connector element which electrically couples and preferably supports the conductive portions in a desired configuration relative to each other. A particularly preferred configuration of the two conductive portions form an open clam shell-type shape, or wedge shape, with the electrically conducting connector element supporting the first conductive portion at an angle from the second conductive element so that a proximal end of each conductive portion couples to the connector element and a distal end of each conductive portion are spaced apart. This particularly preferred configuration and orientation provides an open space between the first and second conductive portion. This open space provides useful additional mounting locations for circuitry, electrical interconnections and the like for components sized to be positioned or coupled therein to thereby facilitate the overall compact construction of the WCD to which the inventive antenna assembly is coupled.
The first conductive portion includes a ground feed attachment member and a signal feed attachment member which may be operatively connected to a ground plane and a radio frequency signal input/output port, respectively. The resonator also includes a slot, or notch, feature formed therein and preferably extending across the first conductive portion, the electrically conducting connector element, and partially across the second conductive portion. The reader should appreciate that the inventive antenna assembly may be fabricated, or stamped, from a section of electrically conducting sheeting (metal, conducting polymer, or other materials plated or coated with conducting material either prior to, or following any applicable plating or coating procedures). In the event that the antenna assembly is fabricated, or stamped, from such a sheet of material, then the first conductive portion, the electrically conducting connector element, and the second conductive portion shall comprise a single conductive element.
In a particularly preferred embodiment, the first conductive portion, the second conductive portion and the electrically conducting connector element of the resonator element are formed as a unitary structure, which may be formed using known technologies and techniques, such as metal stamping, metallic deposition on a dielectric substrate, photo-resist and etching, electroless plating of diverse non-conducting resin-based material and the like. The resonator element may be formed by shaping and manipulating sheet metals such as brass, tin over steel, aluminum, or other suitably conductive material. Preferably, the resonator element comprises brass formed into a sheet and having a thickness of around 16 mils. Alternatively, it will be appreciated that the first conductive portion, the second conductive portion and the conducting element of the resonator element may be formed separately and then assembled into a unitary structure.
The resonator element works in concert with a ground plane of a wireless communication device, with the ground plane integrally formed as a part of a printed wiring board. Preferably, the first conductive portion of the resonator element is attached to the printed wiring board by known technologies and techniques. From there, the ground attachment member and the feed attachment members are operatively connected to a ground plane and a radio frequency input/output signal port, respectively. It should be noted that the ground and feed attachment members should be electrically insulated or else they would short circuit and may not be electrically coupled to the ground plane and/or the input/output signal port. It is understood that suitable insulated and/or shielded connectors such as cables, micro-strips, traces, or the like may be used. To optimize performance, the resonator element is positioned in a predetermined area which is less likely to be covered or overlaid by a hand of a user or otherwise covered during operation of the associated device. In the typical device such a location for the slot wedge antenna assembly of the present invention is adjacent the top of the wireless communication device.
It is an object of the present invention to provide an antenna assembly which may be incorporated into a wireless communication device.
Another object of the present invention is to enhance implementation of an antenna assembly by enabling the bandwidth to be adjusted by manipulating the resonator element.
Yet another object of the present invention is to enable the antenna assembly to be configured to operate at one or more preselected signal frequencies and signal bandwidths.
A feature of the present invention is that the operational bandwidth may be preselected by varying physical parameters of the resonator element either singularly or in combination with each other.
Another feature of the present invention is that the operational signal frequency may be determined and tuned by simply varying physical parameters of the resonator element either singularly or in combination with other physical parameters of the resonator element.
Another feature of the present invention is that there is a single feed point for electromagnetic frequencies.
Yet another feature of the present invention is that fabrication may be accomplished through existing technologies and mass production techniques.
Still another feature of the present invention is that portions of the antenna may be removed to accommodate various components disposed within or proximate to the resonator element and/or the ground plane of antenna assemblies fabricated according to the present invention.
An advantage of the present invention is that the antenna assembly has a low profile which enables it to be used in small articles such as wireless communication devices.
Another advantage of the present invention is that various components of a transceiver device may be positioned within interior regions of the antenna assembly to reduce the overall size of the electronic device, whether or not portions of said assembly are removed to accommodate such various components placement.
These and other objects, features and advantages will become apparent in light of the following detailed description of the preferred embodiments in connection with the drawings.